Environmental chambers (wet cells) have been developed and applied to the examination of whole wet cells in two different ways. In one, the differentially pumped chamber is placed either in a fixed beam microscope (100kV or 1000kV) or in a scanning microscope to give transmission images of whole wet cells. In the second approach the surfaces of wet cells and of wet chromosomes are examined by a new method of wet replication. Excess water is first removed from the specimen which is then placed in an environmental chamber inside a vacuum evaporator. Silicon monoxide is evaporated onto the wet specimen through the chamber apertures. The replica of the wet surface is shadowed and examined in an electron microscope without the introduction of electron radiation damage.